1. Field of the Invention
The present invention relates generally to the field of antennas. More specifically, the present invention discloses a compact omni-directional antenna.
2. Statement of the Problem
Many different types of antennas have been used in the past to receive digital television (DTV) signals. The prior art in this field includes many efforts to approximate omni-directional or elliptical patterns. However, a number of other factors must be accommodated as well in designing a commercially-viable and practical antenna. In particular, antennas are typically required to receive a wide frequency band or a number of separate frequency bands. But, this can tend to add complexity and cost to the antenna design in an effort to provide performance over a wide frequency band. Ideally, an antenna should also be easy to manufacture and be low-cost.
Another factor is the size of the antenna. For example, small portable entertainment modules for use in vehicles and handheld devices impose significant size constraints on antennas, particularly if the antenna is to be located within the device housing.
These design considerations tend to involve trade-offs and compromises to achieve an acceptable antenna design. Therefore, a need continues to exist in the electronics industry for a compact omni-directional antenna that is capable of handling a wide bandwidth and that can be easily manufactured at low cost.
3. Solution to the Problem
The present invention effectively balances these design considerations by providing an omni-directional antenna made of a series of straight conductor segments of varying lengths that form two symmetrical ear-shaped lobes. This configuration generates antenna patterns that are approximately omni-directional or elliptical in the horizontal plane across a wide bandwidth. In particular, the plurality of segments of different lengths and bends of different angles result in antenna patterns that are approximately omni-directional or elliptical in shape across the high VHF and UHF bands.
Another advantage is that the present antenna is compact. The present invention is optimized for compactness and for low cost, so it can be used in ATSC/MH applications inside and outside vehicles and for use indoors or outdoors in HDTV residential applications. Furthermore, the present antenna is easy to manufacture and assemble, and is aesthetically pleasing.